The wireless signal cannot transmit through floor. So I decided to have 3 routers setup at home. Here is my plan to setup. Please let me know if it make sense.

SMC. It is a modern with router. It locates in the first floor, Rogers cable connected to this router. It is the main router to connect outside. I turned off the wireless on the router. It has 4 ports connected to SMC all with wires.
First one connect to D-615(second router)
Second one connect to D-815(third router)
Third one connect to WD Mybook live(NAS HHD)
Fourth one connect to TV player

DLink 615. It is a wireless router. It located in the first floor as well, but close to bedroom. It has 4 ports, but I only use 3 of them connected to PC. Also there are wireless device need connect to this router as well.

DLInk 815. It is a wireless router. It located in the second floor. It connected with 3 PCs and also accept wireless connection. The signal in second floor is very weak if using D-615 wireless connection.

I setup the SMC to 192.168.0.1 with DHCP, D-615 to 192.168.2.1 with DHCP and D-815 to 192.168.1.1. I cannot get rid of the second router, since SMC doesn't have enough wired port. And I need to D-815 because the signal problem. Wondering if this gonna work? Thanks.

4 Answers
4

It should work just fine -- as I understand it, you have a main router which your wireless routers are plugged into, and various equipment plugged into each router.

Since your laptop (or PC with wireless NIC) can only be connected to one wireless network at a time, it doesn't really matter too much how you set up the IP addresses.

One COMPLETELY OPTIONAL suggestion I have for you to make things work even more smoothly though is to configure ONLY your main router to serve DHCP and set up your wireless routers to not do this (if your wireless routers don't support passing IP traffic through from the WAN port without NAT, then you should at least be able to disable the DHCP server options and just not use the "WAN" ports at all -- instead of connecting the main router to the WAN ports just plug it into the regular LAN ports of the wireless routers that have DHCP disabled). This way, you have only one DHCP server managing all your IP addresses, and when you switch to a different wireless router your wireless devices keep the same IPs.

Thank you for your quick replay. I am wondering if you can detail a little bit about how to setup "passing IP traffic through from the WAN port without NAT". Thanks.
–
Simon GuoApr 20 '11 at 2:13

@Simon Guo: You're welcome. Some routers have a feature that allows you to make them operate in a "gateway" mode so that the single public "WAN" port then acts like a regular private "LAN" port. This is particularly useful in a corporate environment where a WiFi point needs to be set up to extend the private LAN over wireless without having to administer another pool of IP addresses. Typically NAT comes into the picture as a means to isolate uninvited public WAN traffic from the private LAN (the default mode for these broadband routers). I hope that helps.
–
Randolf RichardsonApr 20 '11 at 5:36

READ THIS. This was asked a long time ago, but for anyone else who wants to do this, his set up is incorrect and should not work. Here is what to do, the easy, step by step answer. If you understand basic networking, you don't have to read my last paragraph, the important steps are as follows:

Main router, DHCP server ON, this allows the main router to distribute IP addresses to anything and everything. This router will have whatever IP address, for the sake of my answer, call it 192.168.0.1

ALL OTHER ROUTERS set to STATIC IP with DHCP server off. We don't want these routers handing out IP addresses. Set them to 192.168.0.2, 192.168.0.3, ... , 192.168.0.n, however many you have. Depending on the router, you can and should tell the main router to reserve these IP addresses. This is so the main router doesn't give your laptop the same IP address as your 2nd router, which would have an address of 192.168.0.2. Unfortunately, this varies greatly between models, so I can't really tell you how to do this. Trial and error; worst case, you just have to reset your router.

Set each router's channel 6 channels apart, except ones that are far enough. The ones farthest from each other can be set to channel 1, the one in the middle to channel 6. This is so the signals don't get mixed up. If you try to connect two routers wirelessly, then yes, keep them the same signal so they know how to communicate with each other. Wired, keep them 6 channels apart unless they are far enough to not interfere with each other.

set each router to the same SSID, the exact same encryption key and type. This is important. We need for them to replicate one another.

You don't have to read this, but if you want to know what's going on, read on: So the idea here is one router will do the job of handing out IP addresses to other devices. We are treating every OTHER router the same way as we are treating an iPhone, a laptop, or an XBOX 360. The main router hands out IP addresses. So the default gateway is like the standard route to the internet that ALL devices will take. No matter which router something is connected to, it will find it's way through all the cables and signals to the main router. In my example, the default gateway is 192.168.0.1. The default gateway is always the IP address of the main router. The subnet mask should be the same for all routers, for example 255.255.255.0. Each other router's IP address should have all the same blocks as the main one, as in my example, 192.168.0.2, etc. It's like a bunch of houses on the same block. We don't want other routers on a different block. You will find that this isn't always necessary, but if they aren't on the same numbering scheme, then you will not be able to access these routers' home pages. Once in a while, you might also get disconnected and not able to reconnect unless you renew your IP address. This is because your computer is trying to connect to one router, but it doesn't know how to switch to another router that has an IP address that's not on the same block as the one you got disconnected from.

Someone else referred to this setup as a repeater set up. This is not quite correct, because a repeater is, by definition, having a wireless signal REPEATED or extended by connecting wirelessly to the main router. Doing that is difficult unless you have custom firmware. It is easy as pie if you use the same, custom firmware on every router. But it's not always installing such firmware, and if your router is not compatible, you may brick your router. If you don't know what bricking a router is...well...think of a brick, how useful is it? I'll leave that to you. Also keep in mind that repeating a signal halves the bandwidth that you would get from your main router. There are other methods, such as client bridging, and WDS bridging. I'm not entirely sure about the signal quality and bandwidth allocation, but they are different from a repeater.

Remember, always try to adjust network settings for each router by connecting to it hard wired. This is because if you screw something up, you might not be able to connect wirelessly to that router again.

Just a point of order, but in networking parlance a "router" is a device that moves network packets between two (or more) different networks. The normal way of things for a home setup is that one network is your home and the other is the internet.

I bring that up because, in this case, you really want all your devices on the same logical network. That means you want two of your "routers" to really functions as bridges or repeaters, and not be a router at all in the strict sense. To get them to act this way, the simplest option is normally just to turn off DHCP on the "child" routers and run a cat5 network cable from a normal LAN port on the parent to a normal LAN port on each child, rather than to the WAN port. This way, the router on your main level will handle dhcp for everybody, and a computer in the bedroom will be able to do things like print to a printer up on the second floor.

Additionally, you will want to manually give each child router an IP address that is in the same subnet as your dhcp address, but not an address that would be assigned by dhcp itself. For example, if your main router has address 192.168.1.1 and serves dhcp addresses 192.168.1.100 to 192.168.1.150, you could assign your child routers addresses 192.168.1.2 and 192.168.1.3.

Finally, let's talk about channel selection and securing your wireless. You'll want to set all your routers up with the same SSID and security keys, so that you can roam around the house without dropping a connection. Depending on your router manufacturer, you may have to either run an open network or have a small server in your home running something called RADIUS software for this to work, but try it secured first.

To keep everything working together in the best way possible, you don't want to leave your wireless radios to try to autoselect the channels. That works when finding the "cleanest" channel left open by your neighbors, but when you have three devices in the same place you'll end up with them always jumping around to adjust for each other. I'm not sure what the rules are in your country, but in the U.S. I'd set one router for channel 1, another for channel 6, and the final for channel 11. You do this because the channels bleed over to their neighbors quite a bit. This prevents a signal broadcast by a computer at the edge of the range of one router from bleeding over and causing a collision in the space served by it's neighbor.

You can also set the essid of the 3 routers with the same name and so it will broadcast it and will only appear one at the wifi list on your os.

also, for better performance, you should set different wifi channels on each floor so packets won't collide. if you have nearby houses or other 2.14ghz devives, use a wifi analyzer (there are many apps for iphone/android to do this) and check the best choices. in europe we have 13 to chose from.